Device for adjusting the rotational position of a camshaft relative to a crankshaft of an internal combustion engine

ABSTRACT

A device for adjusting the rotational position of a camshaft relative to a crankshaft of an internal combustion engine having a rotor ( 1 ), which is connected rotationally fixed to the camshaft, and a stator ( 2 ), which is driven by the crankshaft. The rotor ( 1 ) or the stator ( 2 ) has a hole ( 10 ), in which a fixing unit ( 3 ) is disposed for fixing a target position of the rotor ( 1 ) to the stator ( 2 ), which engages so it can be detached in a locking link ( 5 ) disposed on the other part. The position of the fixing unit ( 3 ) can be set in the longitudinal direction of the hole ( 10 ) and the hole ( 10 ) is disposed at an acute angle (F) to the adjustment direction (G) of the rotor ( 1 ) relative to the stator ( 2 ).

BACKGROUND

The invention relates to a device for adjusting the rotational position of a camshaft relative to a crankshaft of an internal combustion engine with a rotor connected locked in rotation to the camshaft and a stator driven by the crankshaft, wherein the rotor or the stator has a borehole in which a fixing device is arranged for fixing a desired position of the rotor relative to the stator, wherein this fixing device engages detachably in a locking link arranged on the corresponding other part.

A device according to the class is known, for example, from WO 2005/049976 A1. In the case of this device, a fixing device is provided by which the rotor can be fixed in a desired position relative to the stator. The fixing device can be detached, e.g., hydraulically, so that the relative position of the rotor can then be changed in both directions. The desired position that is defined by fixing the fixing device cannot be changed.

SUMMARY

The objective of the invention is to refine a device according to the class such that the desired position can be adjusted.

For meeting this objective, it is provided that the position of the fixing device can be adjusted in the longitudinal direction of the borehole and the borehole is arranged at an acute angle relative to the adjusting direction of the rotor relative to the stator.

Through the arrangement of the borehole and the adjustability of the fixing device in the longitudinal direction of the borehole, if the position of the fixing device in the borehole is changed, the relative rotational position of the rotor relative to the stator is changed simultaneously. In this way, one possibility is created for the mounting of the fixing device to adjust the desired position between the rotor and stator once. Furthermore, a possibility is created to correct deviations in the desired position due to wear after long operating times of the combustion engine through readjustment of the fixing device.

Furthermore, the fixing device can contact a contact face of the locking link and can be oriented in the longitudinal direction at an acute angle relative to the contact face. Arranging the contact face at an acute angle creates one possibility of controlled fine adjustment in which, first, the adjustment movement of the fixing device controlled by the contact face itself is converted into a change in the rotational position between the rotor and stator and, second, the adjustment movement leads to only a considerably smaller change in the relative rotational position due to the acute angle based on the trigonometric angular relationships and thus a fine adjustment is possible.

The mounting and also the locking and unlocking of the fixing device therefore can be simplified in that the fixing device has a cone on its end engaging in the locking link. Furthermore, the inclined orientation of the fixing device in the area of the locking link is canceled by the cone that can have, in the area of contact on the locking link, a different orientation. In addition, the cone offers the advantage that the orientation of the fixing device relative to the locking link remains unchanged even for a rotating adjustment movement of the fixing device relative to the contact face, and instead completes only a parallel displacement.

The surface or line of the cone contacting the locking link can be oriented, e.g., vertical to the adjustment direction of the rotor, so that ideal transmission of the force exerted during the adjustment movement is realized.

One simple type of adjustment of the fixing device is to be seen in that the borehole has an adjustment thread for adjusting the position of the fixing device in the borehole. Thus, the adjustment is realized by a rotational movement of the fixing device, with this rotational movement being converted by the thread into a longitudinal movement that is then converted, in turn, due to the inclined borehole according to the trigonometric relationships into an adjustment of the rotational position of the rotor relative to the stator. Because all of the conversions of the movements are performed according to a step-down ratio, a very precise fine adjustment is therefore possible.

It is furthermore proposed that the opening of the locking link facing the stator has, in the adjustment direction, a width of at least the specified adjustment path plus the diameter of the borehole divided by cos(90°-F.), wherein F is the angle between the adjustment direction of the rotor relative to the stator and the center axis of the borehole.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in detail below with reference to a preferred embodiment.

The FIGURE is a partial section view of the device according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the sole FIGURE, a section view through a stator 2 and a rotor 1 is shown. The rotor 1 is connected locked in rotation with the camshaft as is adequately known in the prior art, while the stator 2 is driven by the crankshaft. The combustion engine including the camshaft and the crankshaft are not shown for reasons of simplicity. The interaction of the present device with the other parts of the combustion engine, however, agrees with the camshaft adjuster described in WO 2005/049976 A1, so that WO2005/049976 A1 is thus explicitly incorporated herein by reference to the contents of disclosure of the present invention, wherein the fixing device 3 shown in the FIGURE is identical in function to the locking pin 33 from WO2005/049976 A1. The fixing device 3 is arranged oil-tight in a borehole 10 of the rotor 1 and projects into a locking link 5 of the stator 2 in the locking position. The fixing device 3 has a hollow cylinder 9 in which is arranged a compression spring 4 that is supported on an adjustment bolt 7 and forces the hollow cylinder 9 into the locking link 5. For unlocking the fixing device 3, pressure is applied to the locking link 5, so that the hollow cylinder 9 is forced out from the locking link 5 against the spring force. The adjustment bolt 7 has a shaft 11 on which the compression spring 4 is supported and that simultaneously acts as a guide for the hollow cylinder 9. Furthermore, the adjustment bolt 7 has a fixing head 8 with an external thread that engages in an internal thread 12 arranged in the borehole 10. By rotating the fixing head 8, the entire fixing device 3 is moved in the borehole 10 in the longitudinal direction. The thread pair advantageously has a self-locking construction, so that the position of the fixing device 3 is maintained after its adjustment. The center axis “E” of the borehole 10 is inclined relative to the axial direction “D” of the device by the angle “C”. Relative to the adjustment direction “G” of the rotor 1 relative to the stator 2, the center axis “E” then assumes an angle “F”. Due to the trigonometric relationships, the adjustment movement of the fixing device 3 in the longitudinal direction “A” is then converted into a movement “B” of the rotor 1 relative to the stator 2, wherein the stator 2 is viewed as stationary. The adjustment path is then given from S1=S2×cos(90°-F.). So that the adjustment is not impaired, the locking link 5 has an opening oriented in the direction of the rotor 1, whose width corresponds to the adjustment range plus the diameter of the borehole divided by cos(90°-F.). The hollow cylinder 9 is provided on its end projecting into the locking link 5 with a cone surface 6 that contacts a contact face 13 of the locking link 5. The contact face 13 and the cone 6 in the area of the contact on the contact face 13 are advantageously arranged vertical to the adjustment direction “G” of the rotor 1 relative to the stator 2. Thus, the inclined position of the borehole 10 is compensated by the cone 6 and the inclined adjustment movement of the fixing device 3 is converted into an adjustment movement in the adjustment direction “G”. 

1. Device for adjusting the rotational position of a camshaft relative to a crankshaft of a combustion engine, comprising a rotor that is connected locked in rotation to the camshaft and a stator driven by the crankshaft, one of the rotor or the stator has a borehole in which a fixing device is arranged for adjusting a desired position of the rotor relative to the stator, the fixing device engages detachably in a locking link arranged on the other of the rotor or the stator a position of the adjustment device can be adjusted in a longitudinal direction of the borehole and the borehole is arranged at an acute angle relative to an adjustment direction of the rotor relative to the stator.
 2. Device according to claim 1, wherein the fixing device contacts a contact face of the locking link and the fixing device is oriented in the longitudinal direction at an acute angle relative to the contact face.
 3. Device according to claim 2, wherein the fixing device has a cone on an end thereof engaging in the locking link.
 4. Device according to claim 3, wherein the face contacting the locking link or line of the cone is oriented vertical to the adjustment direction of the rotor.
 5. Device according to claim 1, wherein the borehole has an adjustment thread for adjusting the position of the fixing device in the borehole.
 6. Device according to claim 5, wherein the opening of the locking link facing the stator has, in the adjustment direction, a width of at least a specified adjustment path plus a diameter of the borehole divided by cos(90°-F.), wherein F is an angle between the adjustment direction of the rotor relative to the stator and a center axis of the borehole. 